Adjusting the shake of a timepiece wheel set pivoted between two structural elements, particularly between a plate and a bar, also called a cock in the case of a bar for a balance, often optimises the operation of the wheel set and the performance of the movement in which it is integrated. Often, this shake is not adjustable, and results from manufacturing tolerances and operating plays. To overcome this lack of adjustment range, the experienced watchmaker knows how to perform a local deformation of one of the components of the assembly, the least rigid component, for example the cock, to perform a shake adjustment, for example with an amplitude of 20 to 40 micrometers for a balance shake adjustment at T1.
This operation is complex, approximate, costly in terms of time, requires highly skilled personnel, is not reproducible and cannot be automated.
The other option consists in manually modifying the relative position of a bar with respect to a main plate, and particularly modifying the position of a shock absorber bearing holder comprised in the plate, with respect to the bar or vice versa, which requires driving out an element and, as in the case above, results in an effect on the holding force of the shock absorber and/or a deformation of at least one of the components, which is undesirable.
A mechanical adjustment is thus preferred, since it makes it possible to solve problems of reproducibility, is accessible to less highly qualified personnel, and can be automated. However, the space available inside a calibre is not generally sufficient to house an additional adjustment mechanism, especially in the direction of the thickness of the movement in which this type of shake adjustment generally has to be performed.
FR Patent No 1545748 in the name of THE UNITED STATES TIME CORPORATION discloses a device for axially adjusting a balance cock with respect to a main plate, with a cam element whose axis is perpendicular to the plate, including an eccentric head cooperating with a sloping bottom surface of the cock to adjust the position of the latter. This device includes position locking means.
CH Patent Application No 705087A2 in the name of HUBLOT SA describes a member for adjusting the distance between the cock and the plate, provided with an externally threaded part screwed into the cock and including a toothed wheel.